Cook the pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to the package instructions until al dente. Stir occasionally to prevent sticking. Once cooked, drain the pasta and rinse briefly under cold water to cool it down for the salad. Set aside.

Prepare the dressing: In a small bowl, combine mayonnaise, yogurt, Dijon mustard, and lemon juice. Whisk together until smooth and creamy. Season with a pinch of salt and black pepper. Taste and adjust the seasoning if needed.

Combine the salad ingredients: In a large mixing bowl, add the cooled pasta, drained tuna, sweetcorn, diced red bell pepper, and chopped red onion. Gently toss to combine the ingredients evenly.

Add the dressing: Pour the dressing over the pasta mixture. Use a spatula or large spoon to gently fold the dressing into the salad, making sure every piece of pasta and vegetable is lightly coated without breaking up the pasta.

Chill and serve: Cover the bowl and refrigerate the salad for at least 30 minutes to let the flavors meld together. Before serving, sprinkle with fresh parsley or chives for a touch of color and freshness. Taste once more and adjust seasoning if needed. Serve chilled.